1. Field of the Invention
This invention relates to surgical instruments, and more particularly to a locking surgical tool handle system.
2. Related Art
The use of prosthetic implants to replace the natural joints of a body, either as a result of disease or injury to the natural joint, is becoming more and more commonplace. For example, in the replacement of a hip joint, it is very often necessary to replace the natural femoral head with a prosthetic stem fixed within the femur and providing an accurately located and securely held prosthetic head in place of the natural femoral head. The prosthetic stem may by of a press-fit type, or a cemented type.
The procedure for implanting a prosthetic stem includes the use of a broach or rasp, usually as the last step in preparing the proximal femoral shaft for the reception of the prosthetic stem. The purpose of the broach or rasp is to provide contouring of the proximal femoral shaft to the gross geometry of the prosthetic stem, thereby assuring accurate location and good fit. The configuration of the broach or rasp is made to emulate that of the prosthetic stem (and its cement mantle, when used) to enable the attainment of the desired stem shape.
In order to facilitate utilization of such a broach or rasp, it has been suggested that the handle of the instrument be selectively detachable from the instrument tool so that the location of the tool within the femoral shaft can be gauged precisely and used as a means of determining the subsequent location of the prosthetic stem. Further, if the handle is detachable, the tool may be used for location of a trial neck attachment to assure that the length of the reconstructed prosthesis is accurate, and for milling of the femoral calcar (through an opening in the tool) to assure that the bone surface is flat and in line with the face of the tool.
A number of handles for use with releasable broaches or rasps have been proposed in the past. Examples are given in U.S. Pat. Nos. 4,306,550; 4,583,270; 4,587,964; 4,601,289; and 4,765,328. However, these existing handles exhibit a number of problems. Several fail to achieve a tight fit between the tool and handle. A tight fit is necessary to permit good control of the tool during a surgical procedure. Many of the existing handles suffer a high rate of failure between the attachment peg or other interfacial locking component between the handle and tool. A few of the existing designs simply cannot withstand repeated impacts necessary during insertion and removal of a broach or rasp. Lastly, a number of the designs are non-ergonomic, which makes use difficult during a surgical procedure.
It is therefore desirable to provide an ergonomic handle that attaches to cutting tools used during surgery, and in particular, that attaches to rasps and broaches used to fashion the intramedullary canal of the femur during a hip replacement procedure. It is also desirable to provide a design that incorporates proper balance, rigid construction, secure locking of a tool to the handle, quick release to facilitate usage during surgery, and rugged design that survives through repeated impacts during insertion and removal of a tool in surgery.
The present invention provides a locking surgical tool handle that meets these goals.